1. Field of the Invention
The present invention relates to a machine, of the type described, which embodies a suitably journaled, parallel axis, driven roll array including a large diameter primary roll, a small diameter pinch roll disposed closely adjacent but in spaced working relation to the face of the primary roll, and a small diameter bending or forming roll immediately beyond the pinch roll and also disposed closely adjacent but in spaced working relation to the face of said primary roll. All of such rolls are driven so that adjacent faces thereof turn in the same direction.
The initially flat sheet of metal is mechanically fed into the "pinch" point between the primary roll and pinch roll, and then--as advanced by the frictional drive produced at such "pinch" point--the sheet of metal engages the forming roll and thereby is progressively turned or bent downward with a resultant cylindrical curvature imparted to said sheet. This produces a cylindrical sheet metal body which extends about the primary cylinder and until the leading edge of such cylindrical body engages a stop which prevents such leading edge from being reengaged by said "pinch" point. At the same time, the bending roll must--as the essential concept of the instant invention--be retracted from working engagement with the trailing edge portion of the sheet in order to prevent undesirable deformation of the cylindrical, sheet metal body when its further motion about the primary roll is prevented by the stop. The present invention was conceived in a successful effort to implement such concept.
2. The Prior Art
U.S. Pat. Nos. 251,804; 1,354,951; 1,500,906; 2,140,404; 2,742,078; 2,995,171 and 3,279,229 are representative of the prior art known to applicant.
The above prior art--considered singly or together--does not anticipate, nor suggest as obvious, the particular structure of the herein-claimed driven roll array, including the retractable forming roll, and applicant has no knowledge of any prior art disclosing such particular structural arrangement.